Energy attenuation apparatus for a system conveying liquid under pressure and method of attenuating energy in such a system

ABSTRACT

An energy attenuation apparatus for a system conveying liquid under pressure, and a method for attenuating energy in such a system, are provided. The apparatus includes a housing containing at least one chamber, wherein an inlet conduit extends into the at least one chamber, a portion thereof being disposed in the housing and having at least one aperture for introducing liquid therefrom into the at least one chamber of the housing, and wherein an outlet conduit extends out of the at least one chamber, with a portion thereof being disposed in the housing and having at least one aperture for receiving liquid from the at least one chamber of the housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new energy attenuation apparatus for asystem conveying liquid under pressure and to a method of attenuatingenergy in such a system. The invention is particularly suitable forplacement in a system conveying liquid under pressure for theattenuation of pressure pulsations in the liquid, especially in thehydraulic system of the power steering unit of a vehicle. The inventionwould also be suitable for other hydraulic fluids.

2. Prior Art Statement

In hydraulic systems where the operating liquid is circulated by a pump,the pulsations of pressure that are generated by the pump aretransmitted through the conduits and result in noise and/or vibrationbeing produced by the hydraulic liquid. In the case of power steeringfluid in vehicles, such noise and/or vibration is caused, for example,when vehicles are being parked or unparked at idle or very low speeds ofmovement thereof, such as by barely moving into and out of a parkingspace or the like while the wheels of the vehicle are being turned bythe power steering mechanism thereof. In particular, substantial noiseand/or vibration (shudder) can be produced in such a situation when thepower steering fluid passes through the power steering mechanism fromthe fluid pump to the effective steering structure. Further backgroundin this area can be obtained from U.S. Pat. No. 3,323,305, Klees,whereby this U.S. patent is being incorporated into this disclosure bythis reference thereto.

Devices are known for suppressing noise in exhaust gas mufflers. Forexample, U.S. Pat. No. 4,501,341, Jones, provides two side branchresonators, while U.S. Pat. No. 4,371,053, Jones, provides for anapertured tube in a gas muffler housing. Systems are also known forcontrolling the resonation of pressure waves in fuel injection systems.For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through checkvalves that are provided with a flow restriction either directly thereinor in a bypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spoolvalve assembly for controlling flow between inlet and outlet ports.

Applicants are not aware of any teaching of transferring flow of liquidunder pressure from one apertured conduit to another as a means ofsuppressing energy.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved apparatus and method for attenuating energy in a system thatconveys liquid under pressure.

This object is realized pursuant to the energy attenuation apparatus ofthe present invention by providing housing means containing at least onechamber, an inlet conduit extending into said at least one chamber,wherein in a portion thereof disposed in said housing means said inletconduit has at least one aperture for introducing liquid therefrom intosaid at least one chamber of said housing means, and an outlet conduitextending out of said at least one chamber wherein in a portion thereofdisposed in said housing means said outlet conduit has at least oneaperture for receiving liquid from said at least one chamber of saidhousing means.

Accordingly, it is an object of this invention to provide a novel energyattenuation apparatus having one or more of the novel features of thisinvention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a new method ofattenuating energy in a system conveying liquid under pressure, themethod of this invention having one or more of the novel features ofthis invention as set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of the specification in conjunction with the accompanyingschematic drawings, which form a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a simplified automotive power steering system thatincorporates one exemplary embodiment of the energy attenuationapparatus of this invention;

FIG. 2 shows a power steering system utilizing the inventive energyattenuation apparatus;

FIG. 3 illustrates one exemplary embodiment of the inventive energyattenuation apparatus in a specific pressure line or return line of anautomotive power steering system;

FIG. 4 is a cross-sectional view of one exemplary embodiment of theenergy attenuation apparatus of this invention;

FIG. 5 is a view similar to that of FIG. 4 of a second exemplaryembodiment of the energy attenuation apparatus of this invention;

FIG. 6 is a view similar to that of FIG. 4 of a third exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 7 is a view similar to that of FIG. 4 of a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 8 is a view similar to that of FIG. 4 of yet another exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 9 is a view similar to that of FIG. 4 of a further exemplaryembodiment of an energy attenuation apparatus of this invention;

FIG. 10 is a view similar to that of FIG. 4 of another exemplaryembodiment of an energy attenuation apparatus of this invention;

FIGS. 11-13 show portions of inlet and/or outlet conduits that areprovided with alternative configurations of apertures;

FIG. 14 illustrates a simplified automotive power steering system inwhich are disposed two energy attenuation apparatus of this invention;and

FIG. 15 is a graph showing the improvement in pressure attenuationachieved with the energy attenuation apparatus of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

While the various features of this invention are hereinafter illustratedand described as providing an energy or sound attenuation apparatus foran automotive power steering system, it is to be understood that thevarious features of this invention can be utilized singly or in variouscombinations thereof to provide an energy attenuation apparatus forother systems that convey liquid under pressure.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to the drawings in detail, FIG. 1 illustrates a simplifiedautomotive power steering system. During operation, the power steeringpump 11 generates pressure ripples that are transmitted through tubing,such as steel tubing, to the pressure line 12, the power steering gear13, the return line 14, and the reservoir 15, and finally flow back tothe pump 11 itself by means of the supply line 16. It should be notedthat rather than being separated by a hose or similar conduit, thereservoir 15 and the pump 11 could actually be a single unit.

In order to greatly reduce such pressure ripples before they reach thegear 13 via the pressure line 12, and thereby eliminate or at leastgreatly reduce the power steering noise or vibration generated by thepower steering pump 11, the energy attenuation apparatus of thisinvention, which is generally indicated by the reference numeral 20, isillustrated as being disposed in the pressure line 12 between the pump11 and the gear 13. Various exemplary embodiments of the energyattenuation apparatus 20 and components and arrangements thereof areillustrated in FIGS. 2-15, and will be described in detail subsequently.

The energy attenuation apparatus 20 that is shown disposed in thepressure line 12 in FIG. 1 is shown in greater detail in FIG. 4. Inparticular, the energy attenuation apparatus 20 comprises a canister orhousing 21 that in the illustrated embodiment is a two-part housing madeup of the parts 22 and 23 that are interconnected by the ring 24. Inthis embodiment of the energy attenuation apparatus, a single chamber 25is formed in the housing 21. It is to be understood that the size andshape of the housing 21 can vary with the space available to accommodatesame as well as with the existing requirements.

As shown by the arrow, liquid enters the housing 21, for example fromthe pressure side of the pump 11, by means of an inlet conduit 27, suchas a tube or pipe. As can be seen from FIG. 4, this inlet conduit 27extends well into the chamber 25 of the housing 21. In addition, theinlet conduit 27 is provided with a plurality of apertures or holes 28that allow the liquid to enter the chamber 25 from the conduit 27. Fromthe chamber 25, which is also known as a mixing area or a flow controlchamber, the liquid enters an outlet conduit 29 by means of a pluralityof apertures or holes 30 formed therein. The inlet and outlet conduits27 and 29 are sealingly disposed in the housing 21 in any convenientmanner, as indicated schematically at the locations 31 and 32respectively. As shown in FIG. 1 and the schematic view of FIG. 2 of aproposed power steering system utilizing the inventive energyattenuation apparatus, the outlet conduit 29 is connected to thepressure line 12 so that the liquid, in this case power steering fluid,can be conveyed to the gear 13.

Although the embodiment illustrated in FIG. 4 provides for a single,hollow chamber into which a straight inlet conduit extends and fromwhich a straight outlet conduit emerges, it has also been foundaccording to the teachings of this invention that other configurationsare possible. For example, reference is now made to FIGS. 5-10, whereinother housing and conduit configurations of this invention are shown andare generally indicated by the reference numerals 20A-20F, wherein partsthereof similar to the energy attenuation apparatus 20 of FIG. 4 areindicated by like reference numerals that where appropriate are followedby the reference letter A, B, C, D, E, or F.

The embodiments illustrated in FIGS. 5 and 6 differ from that shown inFIG. 4 only in that the chamber 25 is partially filled with a flowcontrol or filler means. For example, the energy attenuation apparatus20A of FIG. 5 shows a housing 21 having a chamber 25 that is partiallyfilled with spherical filler means 34A. These filler means 34A can besolid or hollow beads or balls made of steel, rubber, plastic, or anyother suitable material, and help to increase the dissipation of energy.The filler means 34A, as well as the filler means to be discussedsubsequently, should be made of a non-corrosive material and should beable to withstand temperatures up to 300° F.

FIG. 6 illustrates an embodiment of an energy attenuation apparatus 20Bwherein the housing 21 has a chamber 25 that is partially filled withirregularly shaped flow control or filler means 34B. As was the casewith the filler means 34A of FIG. 5, the filler means 34B can be made ofany suitable material, again solid or hollow, and could even comprisegravel.

The energy attenuation apparatus 20C illustrated in FIG. 7 shows ahousing 21 having chamber means that is not only partially filled withfiller means 34C, such as steel balls, but is also subdivided into aplurality of chambers by baffle plates, as will be discussed in greaterdetail subsequently.

FIGS. 8-10 illustrate how either one or both of the inlet and outletconduits can be bent, rather than having the straight configuration ofthe previous embodiments. For example, the outlet conduit 29D of theenergy attenuation apparatus 20D is bent at right angles prior toexiting the housing 21. Similarly, the inlet conduit 27E of the energyattenuation apparatus 20E of FIG. 9 is bent at right angles after havingentered the chamber 25 of the housing 21. It should be noted that thechambers 25 of the energy attenuation apparatus 20D and 20E could alsobe provided with a flow control or filler means.

In the energy attenuation apparatus 20F illustrated in FIG. 10, both theinlet conduit 27F and the outlet conduit 29F are bent at right angleswithin the housing 21 although they could also extend linearly as insome of the previously described embodiments. The attenuation apparatus20F also differs from the previously illustrated embodiments of FIGS.4-6, 8 and 9 in that the housing 21 does not contain a single chamber,but rather is divided into two chambers 35 and 36. This division of thehousing 21 into two chambers is effected by a further flow control meansin the form of a baffle 37, which in the illustrated embodiment isdisposed in the center of the housing 21. The baffle plate 37 isprovided with a plurality of holes 38 in order to allow liquid to flowfrom the chamber 35 to the chamber 36. Again, one or both of thechambers 35, 36 can be partially filled with filler means. In addition,multiple baffle plates could be provided, either adjacent one another orfurther subdividing the housing 21 into additional chambers, whereby theconduits 27F, 29F could even extend through some of the baffles. Forexample, FIG. 7 illustrates a housing 21 that is provided with threesuch baffles 45, each of which is provided with a plurality of holes 46in order to allow liquid to flow from the inlet conduit 27 to the outletconduit 29 through the various chambers 47-50 into which the housing 21is subdivided by the baffle plates 45. In the illustrated embodiment,the inlet and outlet conduits 27, 29 are illustrated as extending farinto the housing 21, thus extending through two or even all three of thebaffle plates 45. It will be understood that the inlet and outletconduits 27, 29 need not extend so far into the housing 21, and could,if desired, respectively extend through only a single one of the baffles45.

Although the inlet and outlet conduits 27, 29 illustrated in thepreviously described embodiments have all been provided with sphericalholes 28, 30, it is to be understood that any other desired shape couldalso be used. By way of example only, FIGS. 11-13 show some other shapesfor the holes in the inlet and outlet conduits. For example, the inletand/or outlet conduit 40 illustrated in FIG. 7 is provided with ovalapertures 41. The inlet and/or outlet conduit 42 of FIG. 12 is providedwith triangular apertures 43. And the inlet and/or outlet conduit 44 ofFIG. 13 is provided with rectangular apertures 45.

It should also be noted that although in the illustrated embodiments theinlet and outlet conduits are shown as having closed ends within thechamber or chambers of the housing 21, the ends of the inlet and/oroutlet conduits can also be opened, or could also be provided withholes.

Although in the presently preferred embodiments the inlet conduit 27 isillustrated as being provided with six holes, while the outlet conduit29 is shown as being provided with eight holes 30, the number of holesas well as the dimensions and shapes thereof could vary, although it ispresently provided that the inlet conduit 27 have a lesser number ofholes or apertures than does the outlet conduit 29. The reversearrangement would be theoretically possible, whereby the importantfeature is that the number of holes of the inlet and outlet conduitsdiffer from one another. The number of holes, and the other parametersthereof, will vary as a function, for example, of the size of the pumpas well as of the operating conditions. In addition, the holes can beprovided on only one side of a given conduit, or on both sides thereof.In addition, although in the illustrated embodiments the holes areshowing as being aligned with one another in a longitudinal direction ofthe conduit, such holes could also be provided in a staggered orotherwise random configuration. It is expedient to have the holes of theinlet conduit angularly offset from those of the outlet conduit so thatthere is no direct flow between the conduits. If each conduit has onlyone row of holes, these rows could be offset by 180° relative to oneanother. If each conduit has two rows of holes, preferably disposed 90°apart, the rows of one of the conduits would be disposed so as to be 90°from the closest row of the other conduit.

Although the baffle 37 of the embodiment of the energy attenuationapparatus 20F shown in FIG. 10 is illustrated as extending in atransverse direction, a similar baffle plate could also be provided inthe embodiments of FIGS. 4-6, 8 and 9, wherein such baffle plate wouldthen be disposed in a longitudinal direction of the housing 21 betweenthe inlet and the outlet conduits.

It should also be noted that the inlet and outlet conduits need notnecessarily have the same length within the housing 21. In addition, thediameters thereof need not be the same. In addition, the diameter oreven the shape of the holes of the inlet and outlet conduits can differfrom one another.

It should furthermore be noted that although the inventive energyattenuation apparatus 20 has been illustrated in FIG. 1 as beingdisposed between the pump 11 and the gear 13, it is believed that suchan attenuation apparatus could alternatively be disposed between thegear 13 and the reservoir 15 in the return line 14 in order to reducevibration caused by the power steering gear 13. Furthermore, twoattenuation apparatus could be provided. For example, FIG. 14 shows asystem having two energy attenuation apparatus 20, one in the pressureline 12 to a control valve 17 (similar to the gear 13 of FIG. 1), andanother in the return line 14. FIG. 3 illustrates an exemplaryembodiment of an actual pressure or return line (bent to accommodatespace requirements) in which is disposed an inventive energy attenuationapparatus 20, which in this embodiment is provided with an optionalventing means 43.

In one exemplary embodiment of the energy attenuation apparatus 20 ofthis invention as illustrated in FIG. 4, the housing 21 and the inletand outlet conduits 27, 29 were made of stainless steel. The housing 21had an approximately cylindrical shape, and in a small embodimentthereof had a length of approximately 85 mm, a diameter of approximately50.1 mm, and a thickness of approximately 1 mm. The stainless steelinlet and outlet conduits 27, 29 had an inner diameter of approximately9.5 mm (3/8 of an inch) and a thickness of approximately 1 mm. Thediameter of the holes in the inlet and outlet conduits 27, 29 wasapproximately 3.89 mm.

As indicated previously, the pressure pulses resulting from therevolutions of the pump create harmonics and noise. This phenomenon,along with the significant improvement provided by the inventive energyattenuation apparatus, is shown in FIG. 15, wherein pressure is plottedagainst the harmonics order of a given pump, with this pump generatingten pulses per revolution thereof. These 10 pulses are considered as the10th order with the following harmonics being 20th, 30th, etc. Thisgraph, which was plotted for the system of FIG. 1, namely the embodimentof the energy attenuation apparatus 20 of FIG. 4, was effected at asystem pressure of 900 psi and a pump speed of 1200 RPM. The pressure atthe outlet end of the pump is shown in the upper portion of the graph,whereas the pressure in the pressure line downstream of the energyattenuation apparatus is shown in the lower portion of the graph. Thesignificant improvement accomplished with the inventive energyattenuation apparatus can be clearly seen from this graph. For example,for the tenth order of the pump, a reduction of about 56% is achieved,while for the 20th order, a reduction of about 62% is achieved.Subsequent to the 20th order, the pressure pulses are nearly entirelyeliminated.

In view of the foregoing, it can be seen that this invention not onlyprovides a new energy attenuation apparatus, but also this inventionprovides a new method for attenuating sound or energy in a liquidconveying system.

While the forms and methods of this invention now preferred have beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillfall within the scope of the appended claims, whereby it is believedthat each claim sets forth a novel, useful and unobvious inventionwithin the pervue of the Patent Statute.

What is claimed is:
 1. An energy attenuation apparatus for a systemconveying a liquid under pressure, said apparatus comprising:housingmeans containing at least one chamber; an inlet conduit extending intosaid at least one chamber, wherein in a portion thereof disposeddirectly in said at least one chamber of said housing means said inletconduit has at least one aperture for introducing said liquid underpressure therefrom into said at least one chamber of said housing means;and an outlet conduit extending out of said at least one chamber,wherein in a portion thereof disposed directly in said at least onechamber of said housing means said outlet conduit has at least oneaperture for receiving said liquid from said at least one chamber ofsaid housing means, and wherein said inlet conduit and said outletconduit are at least in part parallel to and offset from one another. 2.An energy attenuation apparatus as set forth in claim 1, wherein saidhousing means contains a single chamber.
 3. An energy attenuationapparatus as set forth in claim 2, wherein both said inlet conduit andsaid outlet conduit are provided with a plurality of apertures withinsaid chamber of said housing means.
 4. An energy attenuation apparatusas set forth in claim 3, wherein both said inlet conduit and said outletconduit extend linearly within said chamber of said housing means.
 5. Anenergy attenuation apparatus as set forth in claim 3, wherein at leastone of said inlet conduit and said outlet conduit is bent at an anglewithin said chamber of said housing means.
 6. An energy attenuationapparatus as set forth in claim 3, wherein ends of said inlet conduitand said outlet conduit within said chamber of said housing means areclosed or open.
 7. An energy attenuation apparatus as set forth in claim3, wherein said chamber is partially filled with a filler means, and thematerial of said filler means is selected from the group consisting ofmetal, plastic, rubber, and gravel, and the shape of said filler meansis selected from the group consisting of spherical and irregularlyshaped filler means.
 8. An energy attenuation apparatus as set forth inclaim 3, wherein the parameters of length, size, shape and number andarrangement of apertures, and diameter of said inlet conduit and saidoutlet conduit can be the same or can differ from one another.
 9. Anenergy attenuation apparatus as set forth in claim 3, wherein said inletconduit is provided with six apertures, and said outlet conduit isprovided with eight apertures.
 10. An energy attenuation apparatus asset forth in claim 3, wherein said apertures are aligned or staggered ina longitudinal direction of said conduits, with the apertures of saidinlet conduit being angularly offset from the apertures of said outletconduit.
 11. An energy attenuation apparatus as set forth in claim 1,wherein said at least one chamber has fixed dimensions.
 12. An energyattenuation apparatus as set forth in claim 1, wherein said housingmeans is provided with at least one apertured baffle plate that dividessaid housing means into a first chamber and a second chamber.
 13. Anenergy attenuation apparatus as set forth in claim 12, wherein saidinlet conduit is bent at an angle within said first chamber, and saidoutlet chamber is bent at an angle within said second chamber.
 14. Anenergy attenuation apparatus as set forth in claim 12, wherein both saidinlet conduit and said outlet conduit are provided with a plurality ofapertures.
 15. An energy attenuation apparatus as set forth in claim 14,wherein the parameters of length, size, shape and number and arrangementof apertures, and diameter of said inlet conduit and said outlet conduitcan be the same or can differ from one another.
 16. An energyattenuation apparatus as set forth in claim 14, wherein at least one ofsaid first chamber and said second chamber is partially filled with afiller means.
 17. An energy attenuation apparatus as set forth in claim16, wherein the material of said filler means is selected from the groupconsisting of metal, plastic, rubber, and gravel, and the shape of saidfiller means is selected from the group consisting of spherical, andirregularly shaped filler means.
 18. A method of attenuating energy in asystem conveying a liquid under pressure, said method including thesteps of:introducing liquid via an inlet conduit into a housing meanshaving at least one chamber, a portion of said inlet conduit disposeddirectly in said at least one chamber having at least one aperture forintroducing said liquid under pressure into said at least one chamber ofsaid housing means; and withdrawing said liquid from said at least onechamber via an outlet conduit having at least one aperture for receivingsaid liquid from said at least one chamber, wherein said inlet conduitand said outlet conduit are at least in part parallel to and offset fromone another.
 19. A method as set forth in claim 18, which includes thesteps of:dividing said housing means into a first chamber and a secondchamber via an apertured baffle plate that permits flow of liquidtherebetween; introducing said liquid into said first chamber via saidinlet conduit; and withdrawing said liquid from said second chamber viasaid outlet conduit.
 20. An energy attenuation apparatus for a systemconveying a liquid under pressure, said apparatus comprising:housingmeans containing at least one chamber; an inlet conduit extending intosaid at least one chamber, wherein in a portion thereof disposeddirectly in said at least one chamber of said housing means said inletconduit has at least one aperture for introducing said liquid underpressure therefrom into said at least one chamber of said housing means;an outlet conduit extending out of said at least one chamber, wherein ina portion thereof disposed directly in said at least one chamber of saidhousing means said outlet conduit has at least one aperture forreceiving said liquid from said at least one chamber of said housingmeans, and wherein said inlet conduit and said outlet conduit are atleast in part parallel to and offset from one another; and flow controlmeans disposed in said at least one chamber.